Smart people are just more mentally efficient, why choose a word from your vocabulary that does not embody the true essence of your meaning because it's offensive? Why would someone who is intelligent conform to a social more unless absolutely required? Conformity is for the average, the above average do not conform because they're aware it's purely social conditioning and reject it when unnecessary, the below average do not conform, because they do not even recognize it.

First of all, don't beat around the bush; if anything, all this will do is lead him on. Do what you know is best for the both of you and be truthful with him, so long as it doesn't get anyone killed or supremely embarrased. I'm absolutely sure (from eperience) that your boyfriend will understand where you are coming from and abide by your wishes.